I've always disliked bounties. I'd prefer people contribute because they want to, not because there might be money in it.

I also have concerns that any work that is contributed under a bounty may prove difficult to maintain once the original developer has collected the money: maintaining stuff as Syllable grows is already a problem due to the sheer amount of work involved.

Good point - hence my concern when they do have bounties that there is no requirement to ensuring that the code is clean and maintainable for the long term. I for one aren't apposed to bounties given that I've seen in projects mountains of things that have been ignored by the main developers and little interest in fixing them up by those outside the community. NWAM on OpenSolaris being the prime example of something that has been in development for over a year and lags so far behind NetworkManager it is painful.